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Radiation-Hydrodynamic Analysis of Ti-Doped Sio2 Aerogel Exposed to 4-Ns Laser Irradiation

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Radiation-Hydrodynamic Analysis of Ti-Doped Sio2 Aerogel Exposed to 4-Ns Laser Irradiation University of California, San Diego UCSD-CER-05-01 Radiation-Hydrodynamic Analysis of Ti-Doped SiO2 Aerogel Exposed to 4-ns Laser Irradiation M. S. Tillack, J. O’Shay, E. S. Simpson, C. A. Back and H. A. Scott 10 January 2005 Center for Energy Research University of California, San Diego 9500 Gilman Drive La Jolla, CA 92093-0420 Radiation-hydrodynamic analysis of Ti-doped 10 January 2005 SiO2 aerogel exposed to 4-ns laser irradiation UCSD-CER-05-01 Radiation-Hydrodynamic Analysis of Ti-Doped SiO2 Aerogel Exposed to 4-ns Laser Irradiation 10 January 2005 M. S. Tillack, J. O’Shay,1 E. S. Simpson UC San Diego Mechanical and Aerospace Engineering Department 1 Electrical and Computer Engineering Department C. A. Back and H. A. Scott Lawrence Livermore National Laboratory Abstract We used the Hyades [1] and Helios [2] radiation-hydrodynamic simulation tools to explore the response of low-density SiO2 aerogel carriers doped with trace amounts of Ti and subjected to high-energy pulsed laser irradiation. At sufficiently low density, these targets are expected to respond to laser irradiation more uniformly as compared with solid targets, and therefore provide a better platform upon which to perform measurements of the properties of hot dense matter. In this report we describe our initial modeling results for several cases of interest, with laser 12 14 2 intensities in the range of 4.9x10 to 3.7x10 W/cm , SiO2 densities in the range of 2 to 8 mg/cm3 and Ti doping in the range of 0 to 6%. 2 Radiation-hydrodynamic analysis of Ti-doped 10 January 2005 SiO2 aerogel exposed to 4-ns laser irradiation UCSD-CER-05-01 Table of Contents 1. Background 1.1 Problem description 1.2 Codes and modeling options 1.3 Overview 2. Base Case Analysis 12 2 2.1 Base case results for pure SiO2 at 4.9x10 W/cm 2.1.1 Hyades base case results 2.1.2 Helios base case results 2.2 Effect of opacity models on the base case results 2.2.1 Opacity models and averaging techniques 2.2.2 Comparison of Hyades results with Planck vs. Rosseland averaging 2.2.3 Comparison of Hyades and Helios models using identical (gray) Sesame data 2.2.4 Attempts at spectrally resolved results with Hyades 2.2.5 Comparison of gray vs. spectrally-resolved opacities in Helios 3. Variation of parameters 3.1 Addition of dopant 3.1.1 Gray opacity results with Hyades 3.1.2 Spectrally resolved results with Helios 3 3.2 Increase in SiO2 density from 2 to 8 mg/cm 3.3 Decrease of thickness to 0.5 mm 3.4 Increase of laser intensity from 4.9x1012 W/cm2 to 3.7x1014 W/cm2 3.4.1 High intensity Hyades results 3.4.2 High intensity Helios results, with and without doping 4. Summary and conclusions Acknowledgements Appendices A. Original statement of work B. Input and source files B.1 Hyades base case input file B.2 Source listing for spectral averaging routine B.3 Source listing for Sesame mixture generator 3 Radiation-hydrodynamic analysis of Ti-doped 10 January 2005 SiO2 aerogel exposed to 4-ns laser irradiation UCSD-CER-05-01 List of Figures 1. Electron temperature history at 50 equal-mass zones for the Hyades base case 2. Electron density history at 50 equal-mass zones for the Hyades base case 3. Electron temperature spatial profile at 2.5 ns for the Hyades base case 4. Time history of laser flux in the outermost half of the target for the Hyades base case 5. Charge state history at 50 equal-mass zones for the Hyades base case 6. Electron density spatial profile at 2.5 ns for the Hyades base case 7. Time history of the radial location of the Lagrangian zones for the Hyades base case 8. Electron temperature history at 100 equal-mass zones for the Hyades base case 9. Electron density history at 100 equal-mass zones for the Hyades base case 10. Electron temperature history for the Helios base case 11. Internal and radiated energy for the Hyades base case 12. Internal energy for the Helios base case 13. Radiated energy for the Helios base case 14. Electron density history for the Helios base case 15. Electron temperature spatial profile at 2.5 ns for the Helios base case 16. Electron density spatial profile at 2.5 ns for the Helios base case 17. Comparison of Rosseland and Planck Sesame opacity for SiO2 18. Comparison of single-group Sesame and Propaceos data with Planck averaging 19. Comparison of single-group Sesame and Propaceos data with Rosseland averaging 20. Hyades electron temperature at 2.5 ns using single-group Planck averaging 21. Electron density history for Helios using Sesame gray opacity and EOS 22. Electron density spatial profile at 2.5 ns for Helios using Sesame gray opacity and EOS 23. Electron temperature history for Helios using Sesame gray opacity and EOS 24. Electron temperature spatial profile at 2.5 ns for Helios using Sesame gray opacity and EOS 25. Electron temperature history using the Hyades group radiation transport module 26. Charge state history using the Hyades group radiation transport module 27. Electron temperature history from Helios using a single radiation group 28. Comparison of electron temperature profiles using one or 500 radiation groups 29. Rosseland mean opacity for SiO2, Ti and a mixture of SiO2-6%Ti 30. Internal energy EOS for SiO2, Ti and a mixture of SiO2-6%Ti 4 Radiation-hydrodynamic analysis of Ti-doped 10 January 2005 SiO2 aerogel exposed to 4-ns laser irradiation UCSD-CER-05-01 31. Electron temperature profile at 2.5 ns for SiO2-6%Ti using gray opacities in Hyades 32. Electron density profile at 2.5 ns for SiO2-6%Ti using gray opacities in Hyades 33. Electron temperature history for SiO2-6% Ti using Helios 34. Electron temperature spatial profile at 2.5 ns for SiO2-6% Ti using Helios 35. Electron temperature spatial profile at 2.5 ns for SiO2-2% Ti using Helios 36. Electron density spatial profile at 2.5 ns for SiO2-6% Ti using Helios 37. Contour plot of electron density for the 6% Ti case 38. Time history of laser flux in the outermost 10 nodes of the 8 mg/cm3 target 39. Electron density history for the 8 mg/cm3 target 40. Electron temperature history for the 8 mg/cm3 target 41 Mesh radiative heat flux as a function of time for the 8 mg/cm3 target 42. Time history of laser flux in the 0.5-mm thick, 2 mg/cm3 target 43. Electron temperature history for the 0.5-mm target 44. Electron temperature profile at 2.5 ns for the 0.5-mm target 45. Electron density profile at 2.5 ns for the 0.5-mm target 46. Electron temperature profiles at various times with 3.7x1014 W/cm2 laser intensity 47. Electron density profiles at various times with 3.7x1014 W/cm2 laser intensity 48. Time history of the charge state with 3.7x1014 W/cm2 laser intensity 49. Radial location of the Lagrangian zones with 3.7x1014 W/cm2 laser intensity 50. Time history of the laser flux with 3.7x1014 W/cm2 laser intensity 51. Electron temperature history for SiO2-6% Ti using Helios 52. Electron temperature spatial profile at 2.5 ns for SiO2-6% Ti using Helios 53. Electron temperature spatial profile at 2.5 ns for SiO2-0% Ti using Helios 54. Electron density spatial profile at 2.5 ns for SiO2-6% Ti using Helios 55. Electron temperature history for SiO2-6% Ti using Helios with gray opacities 5 Radiation-hydrodynamic analysis of Ti-doped 10 January 2005 SiO2 aerogel exposed to 4-ns laser irradiation UCSD-CER-05-01 1. Background 1.1 Problem description A new project was initiated at LLNL during 2004 to develop absolute spectroscopic diagnostics. The research involves experiments and theory aimed at investigating atomic kinetics of highly ionized plasmas. The experiments use low-density SiO2 aerogel foams that permit measurement of the temporal evolution of the K and L-shell emission of highly-ionized species using new absolute spectroscopic diagnostics. The data are expected to be sufficiently accurate to enable the creation of benchmarks, which can be used to refine and potentially validate the non-local thermodynamic equilibrium (NLTE) models used at LLNL and other research laboratories. In particular, recombination processes with electron densities in the range of 1019 to 1022 cm-3 for mid-Z elements will be addressed in experiments where an independent measure of the electron temperature is made for a sample with a well-known initial mass density. The experiments will provide temporally-resolved absolute measurements of the emission over a spectral range of 200 to 1000 eV. This project addresses long-standing discrepancies in the study of laser-produced plasmas. Discrepancies between data and calculations of laser-produced plasmas in recombination have been evident since the 1980’s. [3] One example of a large discrepancy is in predictions of the x- ray source duration for times greater than the laser pulse duration. The problem might be in the hydrodynamics; however, there are indications that non-LTE atomic kinetics may be the dominant cause of discrepancies. Recent international workshops on non-LTE kinetics have uncovered major disagreements in predictions from 16 different codes for plasma temperature and density cases that were chosen for relevance to laboratory plasma studies. [4] The inability to accurately model x-ray laser recombination schemes is a prominent illustration that the models are incomplete.
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